Discs on the road… The Insider has his say

He works in R&D for a large bike manufacturer and he wants to talk about disc brakes on road bikes (on condition of total anonymity)

Disc rotor

Who could have imagined that we would ever be talking about improving braking on a road bike. Why bother? Last time I checked going slowly wasn’t the aim of the game. But it is coming, without doubt. Disc brakes on the road will be the buzz groupset development of Eurobike 2012 aka 2013 for the market. Fact.

You don’t need to look very deeply into the comments section of articles on the matter to realise this is dividing opinion and it will continue to do so. I am all for discussion but my problem with most of the negative comments is that they seem misguided or misinformed to me.

Allow me to set the record straight. Discs for the road is not just a sly way to make you buy more bikes and bicycle engineers have not run out of scope to improve the performance of framesets. We are just scraping the surface with carbon technology for the bicycle in so many ways. Stagnation on that front will not be reached for a while yet, but I can explain that another time.

Here is my take on discs…

At Eurobike this last year a lot people were surprised that there was no complete hydraulic disc solution on the market. A full 14months on from the UCI lifting the ban on disc brakes in cyclo-cross and still no solution from the big 2.5 component manufacturers [Shimano, SRAM, and Campagnolo], but from an industry view this was no surprise at all. That is because the industry as a whole is nervous of cyclo-cross. If you look to mainland Europe ‘cross is widely considered to be a sport for a) Belgians and b) Professionals. That's not a big market to aim at. Shimano’s amazing cyclo-cross developments with the CX-50/70 are a great example of how tentative the industry is towards 'cross. Two cranksets and a few front derailleurs is hardly massive investment. And that ladies and gentleman is the important word – investment.

Despite its growing popularity ‘cross will never provide the return on investment to justify the development costs. The numbers just don’t add up. If you consider the amount of money that is going to have to be invested to bring discs to the curly handlebar market in a big way, you can rest assured it is not something that will be done lightly. It will not be a fad and it will not be purely for ‘cross

What is most interesting to me is that without realising it the UCI, with its rule change, has sparked a much greater debate in the industry. What was previously an incoherent rumble going on in the background is now a mainstream topic of conversation. Would discs actually provide any advantage to a road bike? Yes. Frame manufacturers are really pushing hard to come up with a frameset in time for the known launch of the complete solution groupset. Discs are coming to the road market, and the cyclo-cross market will benefit as an aside.

With discs come many benefits, but the real advantage will not be from ultimate braking force. It will be consistent and well-modulated braking in all conditions. It will make sense to you when you ride it you just might have to stomach an initial weight penalty and a barely measureable aero disadvantage. Oh and be a little brave to try something new that you don’t like.

I feel sorry for the likes of TRP, Hope and USE that have invested in the converter solution; a good idea but too late - although all three are probably working on fully integrated solutions themselves – TRP are certainly said to be. My guess on which the manufacturer will break cover with a road disc groupset? Well, it's not a guess I know, but I'm not going to betray any trusts by saying here - it won't be long before you know and anyway it doesn’t take a genius to work it out. With the launch of EPS you are down to 2 from the initial big 2.5. So it's a groupset manufacturer beginning with 'S' that's in the market for some technical innovation.

For me the most interesting aspect of the industry's decision to embrace disc brakes on road bikes is not the technical aspects of the exercise it's simply how much power the UCI has over genuine technical development, despite only 0.001% of the world’s cycling community being directly affected by their legislation. If that ban on cyclocross discs had never existed those many millions of cyclists who have never ridden a cyclocross bike let alone raced one would have been riding road bikes with discs years ago."

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Goatkarma[27 posts]5 years ago

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Another key point I reckon when it comes to discs on road bikes is the ability to then get rid of that damn braking surface on the rims,probably saving a tiny bit of weight but more importantly having a rim that can be all-carbon, have decent braking and have very little in the way of wear n tear. Heard rumours somewhere too that the discs rotors are actually going to have to be much larger than first thought due to heat dissipation(i.e 160mm or 180mm rather than 120mm or 140mm), probably just another rumour though

Yup, exciting in terms of wheel development and braking performance, though the aesthetic angle will be hard as brake callipers have pretty much remained unchanged in terms of looks for a century or so.

How will this affect quick wheel changes in racing? I'm a complete ignoramus when it comes to discs, but it'll slow things down considerably, no? Surely losing larger amounts of time when puncturing is not something pros will be keen on doing.

But they just *will* be too heavy. Compared to a real lightweight road racer.

I've been riding a Genesis Croix de Fer as a commute bike for a couple of years. OK, it's steel, has a pannier rack on etc. But the cable operated discs weigh a bloody ton!

And then there's the maintenance. I would NOT try maintaining those things! You need to be a friggin' watchmaker! The travel distance of the pads is about 0.5mm They get sticky so easily, and upon adjustment using the *teeny, tiny, strippable allen key hole*, begin to rub very easily.

Would there be a significant weight penalty in making the wheels strong enough to cope with the extra forces that disk brakes would cause? I.e. A radially laced wheel would just fold under heavy braking

But they just *will* be too heavy. Compared to a real lightweight road racer.

I've been riding a Genesis Croix de Fer as a commute bike for a couple of years. OK, it's steel, has a pannier rack on etc. But the cable operated discs weigh a bloody ton!

And then there's the maintenance. I would NOT try maintaining those things! You need to be a friggin' watchmaker! The travel distance of the pads is about 0.5mm They get sticky so easily, and upon adjustment using the *teeny, tiny, strippable allen key hole*, begin to rub very easily.

A solution without a problem for road riding I'm afraid.

they won't be mechanical discs, they'll be hydraulic discs, which weigh a great deal less and self-centre

But they just *will* be too heavy. Compared to a real lightweight road racer.

I've been riding a Genesis Croix de Fer as a commute bike for a couple of years. OK, it's steel, has a pannier rack on etc. But the cable operated discs weigh a bloody ton!

And then there's the maintenance. I would NOT try maintaining those things! You need to be a friggin' watchmaker! The travel distance of the pads is about 0.5mm They get sticky so easily, and upon adjustment using the *teeny, tiny, strippable allen key hole*, begin to rub very easily.

A solution without a problem for road riding I'm afraid.

they won't be mechanical discs, they'll be hydraulic discs, which weigh a great deal less and self-centre

And for pros, I don't think the weight is an issue - pro bikes can easily be well under the current weight limit. Neither is the maintenance. There is a real problem with crappy braking on carbon rims (see Geraint coming off the road descending in this year's Tour), so - wheel-change issues aside - they will be welcomed I think? And where the pros go, the high-end market will follow.

Would there be a significant weight penalty in making the wheels strong enough to cope with the extra forces that disk brakes would cause? I.e. A radially laced wheel would just fold under heavy braking

on balance i reckon wheels would have to be slightly heavier, but most of the extra weight is at the hub and the rim could be lighter, so in terms of rotational inertia there's not likely to be much in it

But they just *will* be too heavy. Compared to a real lightweight road racer.

Depends on what you class as a real lightweight

My new bike with disc's will weight in around the 6.6kg mark, fully carbon

So I just went to look on Evans for a similar spec bike and their weight, is 7.08kg thats without disc's

Even a BMC team bike is around 6.4kg

Stu Pomfret wrote:

Would there be a significant weight penalty in making the wheels strong enough to cope with the extra forces that disk brakes would cause? I.e. A radially laced wheel would just fold under heavy braking

and that's presumably with mechanical discs, which are heavier than the new hydraulic road discs will be

Yeah, Avid BB7 mechanical disc's, so it would be lighter with the hydraulic ones

Not a problem at all for pro's, i just don't see them changing for a long time, it will be the younger riders who start out now, long before they even hit pro stage with a bike bought by parents and then go on to become pro's who will start using them, i think

How will this affect quick wheel changes in racing? I'm a complete ignoramus when it comes to discs, but it'll slow things down considerably, no? Surely losing larger amounts of time when puncturing is not something pros will be keen on doing.

Far easier fixing a puncture on my MTB than my road/cross bike - just undo the QR & the wheel drops out and slots straight back in again. No need to faff around unhooking the brake cable or trying to shove the wheel back in before inflating the tyre.
Changing the pads is a lot less hassle than setting up rim brakes too. Force back the pistons, take the old pads out, shove the new ones in and bolt back onto your bike. It may take a couple of goes to get them lined up true, but it involves a lot less swearing than getting rim brakes aligned. The only real pain is changing/bleeding the brake fluid, but you don't do that very often and the dog soon learns that DOT4 fluid doesn't taste nice.
Oh and it feels lovely when you pull the brake lever with one finger and your bike actually stops, whereas when I'm commmuting down Cromford Hill on my Cross Bike I'm not sure I really have the power to stop dead if I need it.

As a long time mountain biker who only got my first road bike a couple of years back, I remember the discs vs rim brakes debate happening all those years ago on MTBs. Discs on even cheap mountain bikes are almost universal now.

Wheel changes - once you've done it a few times and learned the new knack, it really is just as quick as rim brakes.

Weight - look at the weight of a Shimano XTR disc vs rim brake set up and the weight difference even accounting for differing spoke lacing is negligible (plus as previously mentioned any extra grams are at the hub rather than at the rim giving handling improvements).

"feel" - the braking feel and modulation of a good hydraulic disc brake set up really is head and shoulders better than rim brakes.

Buckled rim after hitting a pothole? - this can end your ride on a rim brake bike if its a buckle of more than a few mm, on a bike with discs you'll be far more likely to get home even if the buckle's bad.

A big advantage for MTBs which is less of a factor for road bikes but may still count, is the fact that your braking surface on a rim brake is right down close to the ground constantly in contact with mud/puddles/grit whereas on a disc the braking surface is at the hub nice and high away from the ground. Less cack on your braking surface means better braking and less wear.

Personally I can see hydraulic discs becoming the norm over the next few years on higher end road bikes and gradually trickling down through the range.

My two cents:
1. Most bikes these days has internal cable routing (Smoother lines) and would look bit weird having a front cable hanging around on the fork. Will that be a huge aerodynamic impact? I think so. I also can tell you changing an internal disc brake hose on a MTB is a PAIN!
2. Nobody is talking about the forks themselves. Will they handle the stress?
Just a couple of points - BUT I support the idea of discs. Better braking in the wet is only a good thing.

New axle standard? Will QR live on as we know it, or will we be looking at another more secure mounting?

There was long-standing debate in the MTB world over whether there was a real risk of the braking forces involved ripping the wheel from the dropouts.

The Russell Pinder case was where this came to a head, and was settled between the family and Fox (the fork manufacturers) out of court, so the official investigation and findings were never published.

But QR is all but dead in MTB circles now, on the front end at least.

Eliminating front end flex from suspension forks was a driver for the development of the through-axle systems now in place, but the safety of QR skewers with disk brakes was a hot topic for long time.

I can see why it is happening, but they really are going to have to do something about wheel changes. On the MTB it can be a real faff, on the road bike undo QR wheel drops out bang new wheel in. On the MTB loads of faffing as the disc never slots straight into the dropouts. On the back it is worse as your fighting the rear mech at the same time.

Quote:

But QR is all but dead in MTB circles now, on the front end at least.

News to me, it may be gone on the freeride/dh scene but look at XC (proper XC as in riding up and down hills from A-B) bikes and it is still definitely the majority.

I bought a CX bike as a winter trainer for no other reason that it carried cable disc brakes. It's a no brainer for me. Maintenance in my opinion is easier, set it and forget it, occasionally tighten the pad clearance, renew the pads once in a blue moon. The whole bike stays cleaner without the grinding paste off the rims in the wet, thus reducing maintenance ultimately. I would put my money on disc brakes being defacto standard in 5 years.

How will this affect quick wheel changes in racing? I'm a complete ignoramus when it comes to discs, but it'll slow things down considerably, no? Surely losing larger amounts of time when puncturing is not something pros will be keen on doing.

I have a Croix de Fer with front and rear discs and I've found its actually easier to change the wheel... you don't have to fiddle with the brake thingy to get the tyre past the blocks. The disc just slots straight back into the caliper easy peasy. And I'm no pro mechanic by any means!

Just shows how you can be fooled by how it looks. I'd say try them before making judgements.

Personally, I think they're great (and mine are merely cable operated) but then I'm not obsessed about the extra gram or two in weight - I think it'd be just as easy for me to lose the difference by eating less cake!